I think a preservation would be a great idea. There have been LD rips available before but a high quality preservation would be great.
I've thought about doing a bluray version with the footage spliced in but getting the colour timing to match and getting the LD footage to look decent enough to be worth including will be difficult. I've been recolouring the bluray on and off, as well as for Superman III, but they aren't finished yet.
Check out the colour difference here: https://plus.google.com/photos/113310799378452361657/albums/5726471774840830513?banner=pwa
If in the process of capturing the LD for a preservation, someone could get me the deleted footage in as high quality as possible, I could put together a bluray composite version. Then you would have all viewing options available.
The extended versions of 1-3 have all been online at one point or another, I've got them. They were only ever broadcast in 4:3, so no widescreen version has ever been seen, other than the few deleted scenes on the DVD's that is.